Antioxidants for oils and oil compositions containing the same



Patented Oct. 9, 1951 ANTIOXIDANTS FOR OILS AND OIL CORRO- SITIONS CONTAINING THE SAME Donald R. Stevens, Wilkinsburg, and Arthur 0.-

Dubbs, Springdale, Pa Isslgnors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application December 22, 1847, 7

Serial N0. 793,312

4 Claims. 1

This invention relates to antioxidants for ofls and oil compositions containing the same, and more particularly, it relates to oil compositions containing a compound having the following structural formula:

(pigs 7 1!:

herein R1 is a substituent selected from the w 15 bustion engine. Oxidation of animal and vegetaclass consisting of secondary butyl and tertiary butyl groups, and R: is a substituent selected from the class consisting of alky1,'cycloalkyl, aryl, aralkyl, and alkaryl groups and hydrogen. Compounds of this type are insoluble in water and in dilute aqueous alkali solutions, while soluble in hydrocarbon oils and serve as antioxidants and as bearin corrosion inhibitors when incorporated therein. 1

Gasolines made by the thermal cracking of heavier petroleum oils, and gasolines made by the polymerization of normally gaseous hydrocarbons, contain certain undesirable constituents which are subject to oxidational changes with resultant formation of gums and color-imparting bodies. Catalytic cracking processes, have, in general, given gasolines having better oxygen and gum stability than gasolines produced by thermal cracking processes; however, considerable quantitles of undesirable constituents, for example,

diolefins and cyclic olefins, are still produced. 35

Unless these undesirable constituents are removed or unless their oxidation is inhibited, gasolines are obtained which tend to deposit gums and to discolor in storage and in handling.

Various methods have been employed for removing the undesirable constituents from gasolines such as washing with sulfuric acid or contactin with a solid adsorbent. These methods,

however, have not been entirely satisfactory in that high treating losses are encountered and in many instances, gasolines are obtained which are not sufllciently free from the undesirable gum-forming constituents.

A large number of oxidation inhibitors have been developed for obviating the effects of the undesirable constituents, but many "of these inhibitors are subject to the disadvantage that they are water soluble and soluble in dilute aqueous alkali solutions so that gasolines to which they have been added tend to be deprived or the anti- 6 butyl 2 oxidant material upon contact with water or dilute aqueous alkali solutions.

In addition to gasolines, other petroleum oils such as lubricating oils, turbine oils, transformer 5 oils, and the like, as well asanimal and vegetable oils are also subject to undesirable oxidational changes in storage and in use, which result in definite deterioration of quality and character 01' these oils. For example, oxidation of petroleum 10 lubricatmg' oils results not only in the formation ble oils resultsin the development of rancidity of the oils. 7

It is an object achieved by this invention, therefore, to provide an oil composition having im- 20 proved resistance to oxidational changes in storage and in use.

It is a further object. achieved by this invention tc'provlde an' oil, composition containing a compound .whichwill -inhibit or lly retard a; deterioration or .tholl.

Itisastillfurtherobjectachievedbythisinvention-to' provide 'an oil composition containing an antioxidant "which is substantially insoluble in water a'nd'in' dilute aqueous alkali solutions.

We have discovered that animal oils, vegetable oils and mineral oils, particularly petroleum lubricatins oils and hydrocarbon oils boiling within a 'gasoline' boiling-point range, susceptible to deterioratlon, can be eii'ectively inhibited against such deterioration without substantial modifica tion of the other desirable properties of such oils by incorporating into the oils a small amount of a compound having the following structural !ormula:"'--

'on-n on from groups and'Rz is a substituent selected 50 from the classjccnsistingot aim. eycloalkyharyl.

aralkyL'; groups and As examples or compoimds falling within this class may beincluded bis (2-hydroxy-3-t (butyl 5 -methylphenyllmethane; l,1 bis(2 hydmxy 3"- t butyl-i-m'e'tbylphenyll ethane; 1,1-bis(2-- hydroxy- 8 s-t-butyl fi-methylphenyl) propane; l,l-bls(2- hydroxy-3-t-butyl-5-methylphenyl)butane; 1,1- bis(2-hydroxy-3-t-butyl-5 methylphenyl) isobutane; bis(2-hydroxy-3-t-butyl S-methylphenyi) phenylmethane: bl s(2-hydroxy 3 t butyl methylphenyl) -4-methylphenylmethane; 1,1-bistz-hydroxy-a -t-butyl-5-meth ylphenyl) 2-phenylethane; bis(2-hydroxy-3-sec-butyl-5-methylphenyDmethane; l.1-bis(2-hydroxy-3-sec-butyl- 5 methylphenyl) ethane; l.l bis(2-hydroxy-3 sec-butyl-E-methylphenyl) propane; 1,1 bls(2- hydroxy 3 sec butyl-5-methylphenyl) butane;

1,1 -bis Z-hydroxy-3-sec-butyl-5-rnethylphenyl) isobutane; bis(2-hydroxy-3-sec-butyl-5-methylphenyl) phenylmethane; bis(2 hydroxy-B-secbutyl-5-methylphenyl) 4-methviphenylmethane; 1,1-bis (2-hydroxy-3-sec-butyl-S-methyiphenyl) i-phenylethane: and the like. I

The compounds of the type herein disclosed in addition to stabilizing gasolines are also useful in retarding the oxidation of other petroleum oils. such as lubricating oils, turbine oils. transformer oils, and the like, as well as animal and vegetable oils. We have found that the addition of from about 0.005 to about 2 per cent by weight of the compounds of the type herein disclosed to an oil normally tending to undergo oxidational changes will substantially inhibit or greatly retard the formation of compounds which are corrosive to metals in lubricating oils, will increase the oxygen and gum stability of gasolines and other motor fuels," and inhibit the development of rancidity in animal and vegetable oils. The exact amount of antioxidant used in any particular case-will depend upon the nature of the base oil as conditions to which it issubjected, in any case the amount being suiiicient to inhibit the oxidation of said base oils.

The finished lubricating oil may also contain other "additive" agents includin oilinms and extreme pressure agents. such as aromatic chlorine compounds, stabilized chlorinated paraflins, sulfurized fatty oils and high molecular weight ketonu and esters: viscosity index improvers. such as high molecular weight polymers of isobutylene and the polymers of methacrylic esters; pour point depressants, such as a condensation product of chlorinated wax and naphthalene and a condensation product of chlorinated wax and phenol followed by further condensation of this reaction product with organic acids: detergents, such as nickel naphthenate, metal salts of ethylhexyl salicylate, and metal salts of alkyl substituted phenol sulfides; foam inhibitors, such as organo-silicon oxide condensation products, organo-silicol condensation products, and organo- ,germanium oxide condensation products: and

other oxidation inhibitors. such as alkylated phenols, if d The oxidation with our in ention may be mounted by various methods. They may for example be pre ared by condensing either o-tertiary-butyl-paracresol or o-secondary-bntyl-paracresol and an ali hatic or well as the severity of the inhibitors for use in accordance an aromatic aldehyde in the presence of a condensation catalyst. The following are exam les of a few of the aldehydes which may be used in accordance with our invention: formaldehyde. acetaldehyde. propionaldehyd butyraldehyde, isobutyraldehyde, isovaleraldehyde, pivalic aldehyde, caproaldehyde, benzaldehyde, 0-. m and p-toluic aldehyde. phenylacetaldehyde, a-ethyl caproaldehyde, and the like.

In carryin out the condensation reaction. the

molecular ratio of the butyl paracresol to the aldehyde is advantageously maintained at about 2:1. This ratio is based on an aldehyde monomer such as formaldehyde or acetaldehyde. Ii anthe monomer appearing in the polymer. For.

instance, if trioxymethylene and o-tertiarybutyl-paracresol are condensed, the molecular ratio of the o-tertiary-butyl-paracresol to the 'trioxymethylene would be about 8:1. In carrying out the reaction, it may further be desirable to dissolve the reactants in a common solvent such as glacial acetic acid. Water is formed in the course of the reaction and the reaction product separates out as a liquid or as a solid. Where the reaction product is a liquid, the product may be found in the upper layer, with the acetic acid on the bottom, or Just the reverse may occur. It is therefore essential before discarding either layer to determine which layer contains the product and which layer contains the acetic acid. The product is then separated from the acid layer and washed with water and/or aqueous sodium hydroxide. This washing removes any remaining acid condensation catalyst and also any remaining acetic acid. The, washed product may then be purified by recrystallization from a suitable solvent or by fractional distillation.

As condensation catalysts, we may employ sulfuric acid, phosphoric acid. anhydrous aluminum chloride, boron trifluoride, boron fluoride complexes, ferric chloride, anhydrous zinc chloride, hydrogen chloride, activated clays such as acid treated fullers earth, bentonite, floridin, and the like. The amount of the condensing agent required may be as little as 1 per cent based on the total weight of the reactants. However, larger amounts, as high as 20 per cent by weight, may also be employed. More than about 10 per cent of the condensation catalyst is not ordinarily necessary.

The condensation reaction is carried out at a temperature below about C.' and advantageously at a temperature within the range of from about 0 to about 50 to 55 C. If the temperature is allowed to exceed 100 C. for an as the A. S. T. M. standard test, D525-46 (committce D-2).

EXAMPLE I Bis(2-hydr0ry-3-t-butul-Sfimthytphenyl) methane Into a flask were placed 64.1 grams (0.39 mole) of o-tertiary-butyl-paracresol, 5.9 grams (0.65

'mole) of trioxane and 50 ml. of glacial acetic acid. To this was added a solution consisting of 5 grams of anhydrous zinc chloride in 15 ml. of glacial acetic acid. Anhydrous hydrogen chloride was then introduced slowly below the surface of the solution in the flask. The temperature of the solution rose immediately, and was held at a maximum of about 45 c. by regulating droxy-3-t-butyi-5-methylphenyl) methane.

The ultimate analysis of the bisQ-hydroxy-Zit-butyl-5-methylphenyl) methane as above ob- 1,1 -bis(2-hydroxu-3-t-butul 5 methulphem U- v taobutane- Into a flask were-placed 49.3 grams (0.3 mole) or o-tertiary-butyl-paracresol, 10.8 grams (0.15

tained compared with the theoretical composition was as follows:

7 1 Calculatedior Foum'h bisflrhydroxy- Ultimate Analysis (or. 3-t-butyl-5- Product methyIBbenyD- i me Carbon "i. 8:. g: as. a rogen 0 9.10 9.40

Bydiflerenee.

When bis(2 hydroxy 3 t-butyl-5-methylphenyl) methane, prepared as above described.- was' added to a reference gasoline, having an induction period. of 1.6 hours. in the proportion'of 0.0002 mole per 100 ml. 01' gasoline (0.0681 gram per 1 ml.), the induction period increased to 13.6 hours.

EXAMPLE II 1,1-bis(z-hyaromy-a-t-butyl-s-methylphenyl) ethane Into a flask were placed 65.8 grams (0.4 mole) oi o-tertiary-butyl-paracresol, 3 grams of anhydrous zinc chloride and ml. of glacial acetic acid. To this was added 8.9 grams (0.202 mole) of acei'aldehyde. The mixture thus formed was cooled to between about 0 C. and about 10 C.

in an ice bath after which anyhdroushydrogen chloride was introduced slowly below the surface of the solution. The addition of hydrogen chloride was continued for four hours while main-' taining the temperature of the reactants between about 0 and about 10 C. The reaction mixture was then allowed to stand over night during v um hydroxide,-

mole) o! wbutyraldehyde and 25 ml. oi glacial acetic acid. The mixture thus formed was cooled to between about-0 and. about 10 C. in an ice bath after which anhydrous hydrogen chloride was introduced slowly below the surface of the solution. The, addition of hydrogen chloride was continued for three hours while maintaining the temperature of the reactants between about 0 0. and about 10 C. Awhitecr'ystalline product which formed was washed with 5 per cent aqueous sodithen with water, and recrystallized from an alcohol solution. The white crystals thus obtained melted at 188- 189 C. and were determined to l.1,-bis(2hydroxy-3-t-butyl-5#methchloride,

which time white crystals were formed. These 7 crystals were separated from the reaction mix ture, washed with water, and recrystallized from a 78 per cent aqueous alcoholsolution, The resulting white crystals melted at 105 C. and were determined to be 1,1-bis(2-hydroxy3 t-buty1-5- methylphenyl) -ethane. J p

\ Calculated for Found 1,l-bis(2-hy- UltimateAnalysis for droxy-ii tl-lbutyl- Product B-met lphenyDet one 1 By difl'erence. When 1,1-bis 2-hydroxy-3-t-butyl-5-methylphenyl) ethane, prepared as above described, was added to a reference gasoline, having an induction' period of 1.6 hours, in the proportion 01 1' 0.0002 mole per 100 ml. of gasoline (0.0709 gram per 100 ml.) the induction period increased to 10.5 hours.

- duction period. of 1.0 hours, 0.0002 mole per. ml. of gasoline (0.0765 gram By dii!erenoe.

When 1,1-bis(2-hydroxy-3-t-butyl-5-methylphenyl) isobutane, prepared as above described was added to a reference gasoline, having an inin the proportion of per 100 ml), the induction period increased to EXAMPLE IV as (khpdroxvJ-t-butyl-S meflwlphen uphenyl'metl ane Into a flask were placed 49.3 grams (0.3 mole) or. o-tertiary-butyl-paracresol', 15.9 grams (0.15 mole) or benzaldehydefi grams of anhydrous zinc and 15 ml. of glacial acetic acid. The solution thus formed was cooled to between about 0" and about 10 C. in an ice bath after which anhydrous J hydrogen chloride was introduced slowly below the surface of the solution. The addition oi hydrogen chloride was continued for one hour while maintaining the temperature of the reactants between about 0? and about 10 C. The reaction mixture was then allowed to stand until the next day, during which time a solid material precipitated out of solution. The solid was separated from the liquid reaction mixture and recrystallized from an alcohol solution. A white crystalline product having a melting point or 171-1'l2" C. 'was obtained. product was determined to be bis(2-hydroxy-3-t-butyl-5- methylphenyl) phenylmethane.

Calculated lor Found b|s(2-bydroxy- Ultimate Analysis for 3-t-butyl-5- Product methylphenyliphenylmethane Carbon 83.70 83.61 Hydrogen 8. 94 8. 71 Oxygen 7.36 7.08

I By diflerence.

When bis(2-hydroxy-3-t-butyl 5-methylphenyl) phenylmethane, preparedas above described,

was added to a reference gasoline, having an induction period of 1.6 hours, in the proportion of 0.0002 mole per 100 ml. of gasoline (0.0833 gram per 100 ml.), the induction period increased to 8.6 hours.

EXAMPLE V I Bis(Z-lwdrory-3-sec-butylmethylphenyl) methane l Into a flask were placed 41.1 grams (0.25 mole) of o-sec-butyl-paracresol, 3.8 grams (0.042 mole) of trioxane, 3 grams of anhydrous zinc chloride and 50 ml. of glacial acetic acid. The solution thus formed was cooled to about to C. in an ice bath after which anhydrous hydrogen chloride was introduced slowly below the surface of the solution. The addition of hydrogen chloride was continued for about l5 minutes during which time the reaction temperature was not allowed to rise above about 50 C. A' product consisting essentially of. bis(2- hydroxy 3 sec butyl 5 methylphenyl)'- methane was obtained.

When the product consisting essentially of bis(2 hydroxy 3 sec butyl 5 methylphenyDmethane, was prepared as above described, was added to a reference gasoline, having an induction period of 3.5 hours, in the prooil. As will be noted from the Lauson Engine Test, the addition of bis(2-hydroxy-3-tbutyl- 5-methylphenyl)methane greatly reduced the corrosion of a copper-lead bearing.

{Com ition per ,cent by we ght:

Base oil a- 100 99. 9 99. 7 99. 5 99. 0 (bis (z-hydro -3-tbu tyle'5-methy phenyl) I methane.-. 0. 1 0. 3 0. 5 1.0 Oil inspection characteristics:

Oravity, A. P. I 29. 7 29. 1 29. 0 2S. 9 Viscosity. SUB at- I 100 F 510 520 525 530 21 F 67. 5 67. 2 67. 0 67. 0 Viscosit index--- 109 106 105 104 Color, 1 P. A. 2- 2 2%- 2- Neutralization N o 0. 01 0. 01 0. 01 0. 01 Ash, p r cent 0. 01 0. 01 0. 01 0. 01 0. 01 40 hour results of 11 Engine Test (L-4-prototype .C/L bearing on 081011,

Chevroleteq talent, grams -4 Compounds of the class herein described were also found to be extremely satisfactory as antioxidants tor turbine oils. For example, we

determined the' tendency of a turbine oil to,

oxidize irruse and compared this with the tend-' ency toward oxidation of the same 011 having incorporated therein a small amount of bis(2- hydroxy 3 t butyl 5 methylphenyD- methane.- The test was then repeated using 1,1 bis(2 hydroxy 3 t butyl 5 methylphenyDisobutane as the inhibitor. The tend-.

ency toward oxidation was determined in both cases by-a standardized method of testing steam ran the test in the presence of mls. of di8- 7 tilled water and in the presence of metallic iron and copper. The presence of water necessitated the provision of a reflux'condenser to prevent loss from volatilization.- About 3 feet each of iln'e iron wire and line copper wire were su merged in the oil during the test.

In this test the deterioration of'the oil due to oxidation in the presence of water, iron and copper, is measured in terms of neutralization numbers over a long period of time while the oil undergoing test is subjected to conditions of accelerated oxidation.

In accordance with this test, an uninhibited turbine oil having an initial neutralization number of 0.01 had a neutralization number of 0.2 after only 48 hours under accelerated oxidation. A sample of the same turbine oil having incorporated therein 0.2 per cent by weight of bis(2- hydroxy 3 t butyl 5 methylphenyD- methane had a neutralization number of only 0.16 even after 4128 hours. When 0.2 percent of 1,1 bis(2 hydroxy 3 t butyl 5 methylphenyDisobutane was added to thes'ame tur bine oil. the neutralization number even after 2000 hours was only 0.16. l

In order to illustrate the advantageous results obtained when a compound of the class herein described is added to a vegetable oil, separate samples of linseed oil and linseed oil containing 0.5 per cent of bis(2-hydroxy-3-t-butyl-5-methylphenyllmethane were subjected to an oxidation stability test in a bomb at 100 C. under 125 p. s. i. of oxygen. After twenty-three hours in the test bomb the oxygen pressure on the uninhibited sample had decreased eighty pounds while the oxygen pressure on the inhibited sam# ple had decreased only nineteen pounds, indicating much less absorption of oxygen by the inhibited sample. From these results, it can be seen that the compounds herein described are erfective in suppressing the oxidation of vegetable turbineoils. beingthat of Rogers and Miller (1nd.

Eng. Chem., 19, 308; (1927)), modified in that we controlled the supply of oxygen by meter ing 'to provide 4 liters per hour; we used a 300 ml. sample instead of a 500gram-sample, and

oils.

'The compounds of the class herein described are also useful in inhibiting the oxidation of animal oils. For example, gram samples oflard oil and lard 011 containing 0.5 per cent 0! bis( 2 hydroxy-3-t-butyl-5-methylphenyl) methane were separately agitated and blown with air for six hours at -170 0., the rate 01 air introduction being ten liters per hour.

The following results were obtained:

-Vl5eosity, 110 F., SU at I Uninhibited Inhi The fact that, the compounds of the class herein described inhibit the oxidation ot animal oils a lubricating oil normally tending to undergo 9 oxidaflonai changes and a small amount, sumcient to substantially retard such oxidational changes, of bis(2 hydroxy-3-t-butyl-5-methylphenyDmetlnne.

2. A composition of matter comprising a major amount oi an oil selected from the group consisting of animal, vegetable, and mineral oils normally tending to undergo oxidational changes and a small amount, sumcient to substantially retard such oxidational droxy-3-t-butyl-5-methylphenyi) methane.

3. A composition or matter comprising a major amount of a hydrocarbon oil normally tending to undergo oxidational changes and a small amount,

suilleient to substantially retard such oxidational changes, of a bB(2-hydroxy-3-butyl-5-methylphenylimetlmne, wherein the butyl group is selected from the class consisting of secondary butyl and tertiary butyl groups.

4. A composition 01' matter comprising a major amount of an oil selected from the group consisting of animal, vegetable, and mineral oils changes, of bis(2-hyretard such oxidational changes, 01' a bis(2-hynormally tending to undergo oxidational changes droxy-3-butyl-5-methylphenyl) methane, wherein the butyl group is selected from the class consisting of secondary butyl and tertiary butyl groups.

. DONALD R. STEVENS.

ARTHUR c. DUBBS. REFERENCES CITED The following references file of this patent:

UNITED STATES PATENTS Number Name Date 1,913,367 Calcott June 13, 1933 2,017,827 Bannister Oct. 15, 1935 2,031,930 Buc Feb. 25, 1936 2,202,877 Stevens June 4, 1940 2,270,959 Murke Jan. 27, 1942 2,295,985 Baird Sept. 15, 1942 2,415,833 Mikeska Feb. 18, 1947 2,431,011 Zimmer Nov. 18, 1947 are of record in the 

4. A COMPOSITION OF MATTER COMPRISING A MAJOR AMOUNT OF AN OIL SELECTED FROM THE GROUP CONSISTING OF ANIMAL, VEGETABLE, AND MINERAL OILS NORMALLY TENDING TO UNDERGO OXIDATIONAL CHANGES AND A SMALL AMOUNT, SUFFICIENT TO SUBSTANTIALLY RETARD SUCH OXIDATIONAL CHANGES, OF A BIS(2-HYDROXY-3-BUTYL-5-METHYLPHENYL)METHANE, WHEREIN THE BUTYL GROUP IS SELECTED FROM THE CLASS CONSISTING OF SECONDARY BUTYL AND TERTIARY BUTYL GROUPS. 